1. Field of the Invention
This invention relates to a simulation apparatus for simulating the operation of a working machine, such as a robot and a machine tool operating in accordance with a command program.
2. Description of the Related Art
With the recent sophistication of a production system, a plurality of robots and machine tools have often been combined to make up the production system. For example, a production system in which the door of a machine tool cell formed by surrounding the machine tool with a wall is opened/closed based on a signal from a robot or a PLC (programmable logic controller), so that when the door is open, the workpiece in the machine tool cell is changed by the robot, and after changing the workpiece, the door is closed and the new workpiece begins to be machined by the machine tool.
The robot, machine tool and PLC used in this production system are operated in accordance with a command program, and a test is often requested to be conducted without using a real machine before the actual construction of the production system to check whether the robot and the machine tool operate properly. To meet this requirement, simulation apparatuses of many types have been developed to simulate the operation of units of the machine tool and the robot off line. In addition, as described in Japanese Unexamined Patent Publication No. 63-267183, a simulation apparatus is available in which the operation of a plurality of robots can be simulated on the single simulation apparatus.
In the machine tool or the robot, a plurality of control mechanisms are used in combination, and complicated signal exchange and communication are carried out. However, it is difficult to express this signal exchange and the communication state as a numerical model. Therefore, in the simulation of the operation of the machine tool and the robot, an accurate result cannot be obtained by a method in which like in the simple numerical simulation of the operation, the time is advanced by a predetermined time each time using a numerical model in the same manner as if the time in the virtual space is stopped to determine the state of the machine tool or the robot at each moment. Especially, in the simulation software for the machine tool operation, a machining program is often executed continuously without stopping the lapse of time on simulation while at the same time determining the position (including the posture) of the machine tool at each moment.
On the contrary, the history of robot simulation is so old that even the signal exchange and the communication state can now be expressed as a numerical model, and an increased number of simulation software have come to be used in which the time is advanced by a predetermined time each time on simulation, and the state of the robot can be determined at each moment in the same manner as if the time stops at each moment.
As described above, the robot and the machine tool are often used in combination in the production system. Therefore, the operation of this production system as a whole is desirably simulated and displayed on a display unit. Especially, in realizing the operation in which the door of the machine tool cell is opened, the robot delivers the workpiece into the machine tool cell and installs it, followed by closing the door of the machine tool cell and starting the machining operation of the machine tool, the machine tool and the robot are required to communicate with each other with regard to completion of a predetermined operation using the interlocked commands. In such a case, it is necessary that the elapsed time on the robot simulation and the elapsed time on the machine tool simulation be synchronized with each other to simulate the operation of the production system as a whole, and also be displayed on the display unit at the same time.
However, a simulation apparatus capable of simulating the operation of different working machines such as the robot and the machine tool at the same time has never existed. In addition, even if the simulation software for simulating the operation of the robot and that for simulating the operation of the machine tool are used at the same time, the elapsed time of the two simulation usually fail to coincide with each other, and therefore the result of simulation of the operation of the entire production system configured of different working machines such as a robot and a machine tool could not be displayed on the display unit at the same time. Especially, in the case where the operation of a certain working machine (such as a robot) is simulated using the simulation software which can stop the lapse of time on simulation while at the same time simulating the operation of another working machine (such as a machine tool) using the simulation software incapable of stopping the lapse of time on simulation, the time elapsed on simulation software cannot be rendered to coincide with each other, and it is difficult to simulate the operation of the production system as a whole and display the result on the display unit at the same time.